Ball mill



2 She'ets-Shet l E. SAUMENICHT I BALL MILL Filed Jan. 11 194? May 22,1945.

all! II May 22, 1945 E} SA UMENICHT BALL MILL Filed Jan. 11, 1943 2Shets-fiheet-Z INVENTOR Smmzmcur ATTORNEY Patented May 22; 1945 s v iBALLMILL i i 4 Ernest Saumenicht, Ohatham, v

. ApplicatlonJanuary-ll,194 3; Serial No; mils-5 5 I l 3' Claims.(emu-7o)" Thisinvention mega it mills, and aras; ularly to conical ballmills. r a I An object of the invention is to provide an improvedconical ball mill that 'will'have an in creased output of materialground'to a maximum fineness. I

' It is another objectof the invention to provide animproved conicalball mill wherein the pulp is more readily' discharged through thedischarge throat of the'milly h f It is a still further objectto providea conical ball mill that has particular merit in wet grinding in thatthe pulp level can belowere'd substantially below the discharge'throat'of the mill and thereby increase the maximum eiliciency of the' mill.

'It is another object of the invention to provide a. ball mill thatisadaptedio'r either wet'or dry grinding wherein the i'pulp" is preventedfrom building up at the discharge throat by permittin removal of thepul'p ff rom 'the "discharge throat at a level below the'maxin'i'umnormal heightbf the pulp in the discharge throat. It isanother object of 'the'invention to provide a discharge throatforaconic'al 'ball mill thatisconstructed andarranged to lower thepulp-level at the discharge throat to prevent the material from crowdingat the dischargethroat and thereby'permit free discharge thereof toincreasethe capacity of the ball mill, the discharge throat being alsoconstructed and arranged in a manner that the pulpthat dischargesthrough the discharge throat below=the-lowest point of thedischargeopening is carried bodily around'the discharge throatto'p'ermit its gravity discharge into asuitable carrier; g

It is another object of the invention tozprovide a conical ball millhaving means in the discharge throat for bodily liftingthe pulp from thedischarge throat and permitting the same to discharge therefrom by meansof gravity.

A further object .of this invention is to'provide a. conical ball millhaving a discharge throat therein that is constructed and arranged in amanner that the pulplevel is substantially lower than the normaloverflowlevel at the discharge throat sothat themassing of the pulp atthe'disg charge throat, is relievedwhen used for, either dry or wetgrinding; the'lowering of the pulp level being accomplished withouteffecting the efliciency of the grinding operation in the ball mill andwithout altering the general conical shape of the discharge end of theball mill to permit maximum grinding or the material to obtain maximumfineness of the material before it is discharged th h th d ch e thr t: 1

Further objects and advantages will become ap the drawings and thefollowing-dd parent tromscription, v

In the drawingsz i a h Fig. 1 is a side elevational view of a conicalball mill. I

Fig. 2 is a longitudinal cros s seotional view of a conicalball millhavingthe improved discharge throat of this invention. Q h i i Fig. 3 isan enlarged end elevational view of the discharge grates in thedischarge throat taken substantially along line 3'3 of Fig. 2. v

Fig. l is an enlarged cross sectional view taken alongline.44 of Fig,2 ai i Fig. 5 is a cross-'sectionalview oflaportion of the improveddischarge throat showing aslightly modified arrangement thereof.

r Fig. 6 is a cross-:sectional-view of another modified arrangement ofthe discharge throat'for the ballmill. i Fig. 7 is a transverse,cross-sectional view of a alonglinellofFigfil p In thisinventionthe'ballmill l0 consists offa discharge throat disclosed in'Fig6 and'is taken shell II that may be fabricated in any conven-. j

tional manner. The shell consists of a' conical inlet end l2, acylindricalpo'rtion' l3 and a conical discharge end M. The conicaldischarge end I4 is constructed so that th'e'inner surface of the shellforms an angle of approximately 30 with the axis of themill Hi1 A linerI5 is provided within the shell I I that may be constructed in sectionsto permit removal and replacement of any portion of :the liner thatshould become worn or damaged. A trunnion IGhaving an opening l1therethrough is provided on the inlet end {2 of the shell ii, and a;trunnion 21 is provided on the outlet or discharge end: of the shell ll.These trunnicns I6 and 2'! are supported in suitable bearing members -18and I9, respectively; whereby the shell H is rotatably mounted.

A gear 20 is secured to the shell H around the discharge and I4 thereofthat engages a pinion 2i providedon an end of a drive shaft22 extendingfrom an electric'motor 23. The pinion 2| and the gear 20 may beeither'of the spuror herring bone type. Also the direct drive connectionfrom the electric motor 23 may be changed to' a belt drive, or any othersuitable mechanism, for rotating the ball mill. mean he provided. i a

The inlet opening n for the ball mill in has a feed chute associatedtherewith f for feeding material into the ball mill 1.; The materialdischarged into the .chute zimay be controlled in any suitableman'ner toregulate the quantity 7 whereby the'finely ground material has a tendofthe material that is fed into the ball mill and v ency to accumulatefurther back 7 toward the thus regulatelthe rate of discharge of themate-j center of the mill and thus reduce-the operating. rial from theball mill. The ball mill I0 is proefficiency of the mill.

I vided with a discharge opening '25 provided in 5 Inthis inventionthere is provided an irnproved v the cone-shapedend wall l4of the shellII that discharge throat for a ball mill that'will permit has adischarge flange 26 associated therewith. I "dischargeof the, pulp :froma lower level than for discharging pulp into a suitable carrier. wouldnormally occur in' the overflow type of dis-f The description of theballmill just given is a charge arrangement,.and When the mill is usedgene'lfal i iifi l i. .7 t .t 7 that is adapted for iherwet or dnygrind'ingr se retes when used for drylgr indiflg; It is-well-known thatconical ball mills con-1 Thedischarge 'throatp3flisprovided with astructed and arranged in a manner disclosed in i plurality of triangularshaped grates 3| that are t app haverthel peculiar feature T 12 eshapedarcuately transversely so that when'a segregating the balls in the millso that the lar g'e 'gffiuiality of the grates 3| aredisposed inengageballs are disposed within the largestdiametercinentwvithaonefianother thatacone-shaped grate r of the ball mill andas the diameter of the shell; .memberis provided. Each of the grates 3|are of the mill decreases toward'thedisliargififbefi ing that the ballsautomatically seg e fi'e'f mm- 1: dischargefithroat 30 of the ball milland are spaced selves so thatthesizeofthe ball decreases-toward 20 fromthe wall of the discharge endof themill by s trie fifslia ga t rhtsaiiaiteaeat sim meats;st angestzwdmeaa dygs ment with the liner 5 andthe race eyicflof 'tPTe giatEsQ sinarrgnnrem e ate a is to' bedischargedfrdir'r as was a i it eerates 3=1land l?513 plVenbabmgignaoith he charger-opening. ar-scremM-tsrrow r .edvovge g pex end of thedischarge throatg a o t ,preyeht OfithbfillSfifOm within -1 h 1 1in'ibroveddisoharge throat; usedifor wet grind+ mg, the 'materialsisiifiedrsintowtheleballimills ffl through theeihletmrofeedaopening*l'fLc: a l-meamill,

7 t rGaPWHi h sithefn mar-pr cti Abra? teaser-wan df' the discharge 'e 7whenaheebammmwstmsinvention; Fwithcthe will carry it from the mill.

reaches the lowermost edge of the opening 25 whereby the general forwardmotion of the pulp However, in this invention the pulp can-be removedfrom the mill at a lower level than that established by the lowermostedge ofthe discharge opening'25;

. In previous conical mills it was necessary'to lower the position of.the discharge opening and thus lower the general level of the pulp inthe mill ifa lower pulp level was to be obtained. This conditionsubstantially reduced the output capacityof theconical mill because toreduce the general level of the pulp it was required that less materialbe fed through the mill.

In this invention, however, the openings 35 in the grates 3| permitthepulp topass into the spaces 35 when they are disposed at a, level beneath the discharge opening 25 so that the pulp will be removed fromwithin the interior of the ball mill at a lower level than that normallyestablished by the lowermost edge of the dis charge opening 25. Thispermits relief,of the crowding, or packingof the pulpat the dischargethroat, because it has a greater surface area of escape from the'throat.It will be noted, how-- ever, that even though the pulp levelis loweredin the mill, and can be lowered to the point indicated by the dottedline 4|, that the general level of the pulp in the forward, or feedingend of the mill has not been lowered. Since the general level of thepulp has not been lowered the volume of the material capable of beinghandled in the mill is not reduced and the capacity thereof remains thesame, andis actually increased because the pulp is removed from thedischarge throat before there is any tendency of the pulp to pack at thedischarge throat. I

It is, of course, understood that the ball mill I is rotating during itsoperation, and as viewed an annular ring 45 issecured to the end of thewall 14 of the shell "whereby a space 35 is provided-between the grates3| and the annular ring -46, and the vanes 32 engage the annularuring 45to'supportthe grates 3| in the throat 30. The

support trunnion Ila may be carried bythe annular ring in place of beingupon the shellwall M, as "heretofore described. The operationof themodified form of structure is identicalas heretofore describedregardless of whether a dry grinding or wet grinding operation is beingperformed. 7 i

- In Figs. 6 and '7 there is shown a modified arrangement of a throatopening for a ballmill wherein thepulpis picked up bodily from" thelower portion of the mill and carried to the upper portion to bedischarged by gravity in the same manner that the vanes 32a, heretoforedescribed,

pick up the pulp within the space '35 and carry it to the top of themill so that it will be dis-i charged by gravity. In the arrangementshown in-Figs. 6 and 7, the lining andshell 5a of the from theright-hand end of the mill shown in Fig, 2, is rotating in a clockwisedirection. Therefore, the pulp that discharges through the openings 35in the grates 3| is picked up by the vanes 32a and carried upwardlybodily until the'vanes pass over the horizontal center and begin to bedisposed angularly relative to the horizontal as shown in the upperportion of Fig. 3. When the vanes 32a are in the position indicated bythe vane 32aa, see Fig. 3, the pulp will slide forwardly on the vaneover the blank wall surface 35 of the grate 3| and thus be dischargedthrough the flange 25 adjacent the opening 25, this discharge,therefore, being by gravity flow.

When the ball mill is to be used for dry grinding the operation thereofwill be identical with the operation just described.

- In Fig. 5 there is shown a slightly modifie form of the structure ofthe throat of the ball mill of this invention. It will be noted in Fig.2

I that the spaces 35 have been-provided by indischarge end of theconicalmill is continuous to the-discharge opening 5|, a discharge flange 49being positioned adjacent the discharge open ing 5|. A plurality ofvanes 52 are positioned radially within the discharge throat 55 inengagement with the wall 50. A grate 53 is positioned adjacent theforward ends of the vanes 52 and is provided with a'plurality ofopenings 54 through which pulp can pass through the discharge open-Since the vanes are secured to the wall 50 they will, of course, rotatewhen the ball mill'rotates-f Th'e pulp passing throughthe openings'54'in'thegrate53 will be caught by thevanes 52 and movedbodily'upwardly until the vanes 52 have a downwardly inclined angle' asindicated bythe vane 52a, shown in Fig. '7, whereby the pulp will slidedownwardly along the vane against the wall 50 to the discharge opening5| and thereby be discharged from the ball mill by gravity flow.

, It will be readily apparent that the vanes 52 will maintain a lowerpulp level at the discharge 3 throat 55 than if the pulp was permittedits normal flow through the ball mill until it was forced I to overflowthe lowermost edge of the opening 5|, and this would be true whether theballmill was used for dry or wet grinding.

In the foregoing description it will become apparent that the pulp levelin the ball mill-can readily be controlled by the position of theinner-,

most openings 35 in the grates 3|, or by the in nermost ends of thevanes 52. The position of these openings, or the ends of the vanes, ispredetermined according to the size of granule that is to be dischargedfrom the ball mill. Also, the position of the pulp level could be madereadily adjustable by providing suitable means for closing certain ofthe rows of openings provided in the grates 3|, or by controlling theposition of the innermost ends of the vanes 52, all of which changes inpulp level at the discharge throat can be controlled without reducingthe general level of'the pulp in the mill, or without reducing thedischarge capacity of the mill regardless of whether it is used for wetor dry grinding. Also, the construction of the discharge throat in thisinvention reduces the horizontal travel or the pulp through the millwithout reducing the efficiency of the grinding operation because thegeneral level of the mass in the mill is above the pulp level at thedischarge throat. I

While the apparatus disclosed and described

